EP0746892B1 - Pre-regulator with protection against voltage ringing on turn-off - Google Patents
Pre-regulator with protection against voltage ringing on turn-off Download PDFInfo
- Publication number
- EP0746892B1 EP0746892B1 EP95931389A EP95931389A EP0746892B1 EP 0746892 B1 EP0746892 B1 EP 0746892B1 EP 95931389 A EP95931389 A EP 95931389A EP 95931389 A EP95931389 A EP 95931389A EP 0746892 B1 EP0746892 B1 EP 0746892B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- circuit
- voltage
- coupled
- output
- turn
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/16—Modifications for eliminating interference voltages or currents
- H03K17/168—Modifications for eliminating interference voltages or currents in composite switches
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/66—Regulating electric power
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
- H02M1/4208—Arrangements for improving power factor of AC input
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/16—Modifications for eliminating interference voltages or currents
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/16—Modifications for eliminating interference voltages or currents
- H03K17/161—Modifications for eliminating interference voltages or currents in field-effect transistor switches
- H03K17/165—Modifications for eliminating interference voltages or currents in field-effect transistor switches by feedback from the output circuit to the control circuit
- H03K17/166—Soft switching
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
Definitions
- the present invention generally relates to power supply circuits and particularly to a switching pre-regulator power integrated circuit which is protected against harmful voltage ringing upon turn-off of the switching power transistor. More particularly, the present invention relates to an AC/DC converter circuit comprising:
- Such an AC/DC converter circuit is known from European Patent Application EP-A-0 622 889.
- a major problem in switching type pre-regulator circuits is that a large voltage ring or oscillation occurs at the drain of the switching power field effect transistor (FET) device upon turn-off of the FET device.
- FET switching power field effect transistor
- This problem is especially acute when there is an inductance in the circuit, either in the form of a discrete inductor or the ever present parasitic inductance common to these types of circuit.
- the power FET device exhibits a parasitic capacitance between its drain and source electrodes.
- the current through the inductor or parasitic inductance cannot drop to zero instantly and so it generates a large voltage ring (oscillation) at the drain of the power FET device. This ringing voltage can often be large enough to destroy the power FET device.
- the snubber circuit consists of a resistor and capacitor connected in series circuit between the drain and source electrodes of the FET device.
- the additional components, resistor and capacitor add to the cost of the circuit and also increase the switching losses in the circuit.
- the European Patent Application 0 380 881 describes a protection circuit for a power MOSFET which drives an inductive load.
- This snubber circuit comprising two stages, regulates the gate current of a MOSFET in relation to the drain-to-source voltage at turn-off so as to clamp transient inductive voltages to a non-destructive level.
- a current source is activated to discharge the gate capacitance and the snubber circuit controls the magnitude of such current in relation to the sensed drain-to-source voltage so as to stabilize this voltage at a non-destructive level.
- a current injection circuit supplies additional current to the gate so as to sustain conduction in the MOSFET, again in relation to the sensed drain-to-source voltage.
- the current injection circuit is disabled and the conduction of the current source is increased to complete the turn-off of the MOSFET.
- pre-regulator circuit also provides an attractive alternative to conventional switch mode power supplies (SMPS) because it avoids the use of inductive components, although some small parasitic inductance may still be present. Furthermore, since the pre-regulator circuit does not utilize a high-frequency switching transistor, it develops a much lower EMI. However, prior art pre-regulator circuits for power supply applications typically are difficult to integrate because it is hard to achieve accurate low power sensing at high voltages and because peak switching currents as high as 10 amps can appear in the circuit.
- SMPS switch mode power supplies
- An object of the invention is to provide a pre-regulator circuit which effectively suppresses, or at least substantially reduces, the ringing voltage that otherwise occurs upon turn-off of the switching power FET device in the circuit.
- the above object can be achieved by the above specified AC/DC converter which is characterized in that the switching transistor is a slow turn-off transistor, the AC/DC converter circuit further having a parasitic inductance that normally produces a large ringing voltage at the drain electrode of the switching transistor, said slow turn-off transistor being responsive to said control signal to slow the decay of current therein and thereby slow the decay of current in the parasitic inductance so as to reduce the level of ringing voltage on turn-off of the switching transistor.
- This power supply circuit substantially reduces any voltage ring across the switching power device by using a slow turn-off as the switchable power device.
- the invention is based upon the recognition that the slow turn-off characteristic of a slow turn-off switching transistor provides a simple and inexpensive expedient to the problem of reducing the amplitude of the ringing voltage that normally occurs on turn-off of the power device.
- the current in a slow turn-off switching transistor drops off to zero slowly, thereby allowing the current through the parasitic inductance to decay slowly to zero, which in turn reduces the level of any voltage ring.
- a lateral insulated gate bipolar transistor (LIGBT) device can be used as the slow turn-off switching transistor.
- the pre-regulator circuit of the aforesaid published European Patent Application includes a load capacitor in series with a switching power device, in that case a field effect transistor.
- the capacitor voltage is differentially sensed by a control circuit which turns off the power device when the capacitor voltage reaches a predetermined voltage level. If there is any parasitic inductance in the drain circuit of the FET power device, a large voltage ring will appear at the drain of the FET power device when it is turned off.
- the use of an LIGBT device, such as that described in U.S. Patent 4,989,058, or other device with a similar slow turn-off characteristic in place of the FET power device will correct or substantially reduce the voltage ring which otherwise would occur upon turn-off of the FET power device.
- a high density 500 volt LIGBT device which can deliver a peak current of 10A with a very low on-resistance of about 0.33 ohms at a low on voltage of 3 volts is available for use.
- an on voltage of only 3 V the power dissipation in a 150 watt system requiring 1A of current is only 3W, resulting in an efficiency of 98%.
- Fig. 1 of the drawing shows a diagram of a preferred embodiment of the invention, incorporated into a power IC pre-regulator circuit of the type described in detail in the published European Patent Application EP 0 622 889.
- the pre-regulator circuit receives a sinusoidal AC input voltage of 115 V, 60 Hz (or a 50 Hz voltage) at a pair of input terminals 1, 2.
- This AC voltage is applied to a pair of input terminals of a full wave rectifier bridge circuit 3 at whose output terminals a full wave rectified DC voltage is developed.
- This DC voltage is applied to an output filter capacitor 4.
- An output voltage is available for a load circuit (not shown) at the DC supply voltage output terminals 5, 6, which are coupled to the output capacitor.
- the circuit is readily adaptable for use with a variety of loads, such as a TV receiver, a DC motor, a halogen lamp, etc.
- a differential voltage sensor circuit 7 has a first high voltage input terminal coupled to DC output terminal 5 via a series connected resistor 8 and has a second high voltage input terminal directly coupled to the output terminal 6.
- the input of the differential voltage sensor thus is connected in parallel with the filter capacitor 4.
- the differential voltage sensor is preferably constructed in the manner described in the published European Patent Application EP 0 621 638, but is not limited to that topology.
- the differential voltage sensor may alternatively be constructed with resistive voltage dividers and a comparator for comparing the attenuated voltage difference between the voltages at output terminal 5 and output terminal 6.
- the output 9 of the differential voltage sensor circuit 7 is coupled to a first input of a logic circuit 10.
- a drain voltage sensor circuit 11 has its input coupled to the drain electrode of a power switching transistor 12 via a resistor 13 and has its output coupled to a second input of the logic circuit 10.
- the drain voltage sensor circuit 11 may be constructed with a resistive voltage divider and a comparator for comparing the attenuated voltage with a reference voltage.
- Another very suitable circuit for monitoring the drain voltage of a transistor is described in the published European Patent Application EP 0 626 581.
- the published European Patent Application EP 0 622 889 mentioned above also includes a differential voltage sensor circuit and a drain voltage sensor circuit suitable for use in this invention.
- a high voltage surge sensor circuit (not shown) may be provided in order to sense a voltage surge due to a lightning strike on the supply line.
- the input of this circuit would then be coupled via a resistor to the line connecting one output terminal of the rectifier circuit 3 to the DC output terminal 5.
- the output of the voltage surge sensor circuit would be connected to a further input of the logic circuit 10.
- the voltage surge sensor circuit would monitor the supply voltage and if it sensed a large voltage surge, it would turn on the power switch 12 thereby to connect the large filter capacitor 4 across the supply lines.
- the filter capacitor would then absorb the energy due to the lightning strike.
- the power switch 12 consists of a lateral insulated gate bipolar transistor (LIGBT) device which is characterized by its slow turn-off characteristic.
- the LIGBT device 12 is connected in series circuit with the output capacitor 4 across the DC output terminals of the full-wave rectifier circuit 3.
- the gate electrode of the LIGBT device 12 is triggered by a drive signal applied to it from the output of the logic circuit 10 via a drive amplifier 16.
- the switchable power device 12 and the control circuits therefor may be conveniently integrated on a single power IC chip illustrated diagrammatically by the dashed box 17 in the drawing.
- the power supply for the circuit elements of the power IC 17 is derived from a temperature compensated bandgap reference voltage regulator 18 which produces, for example, a 7.5V DC voltage supply.
- the power IC may also include an on-chip temperature protection circuit 19 having an output coupled to a further input of the logic circuit.
- the apparatus shown in the drawing can operate as a 500V pre-regulator power IC which converts AC voltages from 30V to 260V at input terminals 1, 2 into DC voltages in the range of 24V to 150V for operation of a load connected to output terminals 5, 6.
- the load can include a TV receiver, a DC motor, etc.
- the LIGBT device 12 then operates as a 10 amp power switch.
- the full wave diode bridge circuit 3 rectifies the AC supply voltage.
- the output voltage at terminals 5,6 is continuously monitored by the on-chip differential voltage sensor circuit 7.
- the differential voltage sensor circuit senses the differential output voltage at terminals 5, 6 during the time when the input voltage is rising and produces a control signal that is applied to the gate of the LIGBT device 12 via logic circuit 10 and driver amplifier 16.
- This control signal turns the power switch 12 off when a predetermined output voltage is reached.
- the power switch remains off until the next input voltage cycle, when the output capacitor 4 is recharged by turning on the power switch 12.
- the capacitor is recharged about once every eight ms, and the output maintains a constant voltage whose ripple is determined by the size of the capacitor and the value of the load current.
- the capacitor supplies the load current when the power switch 12 is off.
- the DC output voltage is limited to the predetermined value of the output voltage for an Ac input voltage variation of 30V to 260V. Good output voltage regulation is obtained because the control circuit is regulated by sensing the output voltage.
- the drain voltage sensor circuit 11 senses the voltage at the drain of the LIGBT power switch 12 when the input voltage is falling and supplies a second control signal to the gate of the power switch via the logic circuit 10 and driver amplifier 16. The latter control signal turns the power switch on again when the input voltage reaches a safe turn-on level.
- the power switch In order to replenish the charge on the capacitor that is lost to the load during the time when the power switch 12 is off, the power switch must be able to draw peak currents as high as 10A in just a fraction of the AC cycle period.
- the LIGBT device is ideal in the case of low frequency operation since it is a high current density device with a low on-resistance value and has a relatively slow turn-off characteristic.
- the bandgap reference voltage regulator 18 can tap off its input voltage from output terminal 5 of the apparatus.
- the voltage regulator 18 supplies, for example, a 7.5 volt DC supply voltage to the various circuits on the power IC chip 17, such as the differential voltage sensor, the drain voltage sensor, etc.
- Fig. 2 shows some typical voltage and current waveforms of the turn-off operation. These waveforms provide a comparison of the gate voltage of the power device, the drain current through the power device, and the drain voltage of the power device when a prior art fast turn-off device (e.g. LDMOS) is used and when a slow turn-off LIGBT device is used as the power switch in accordance with the present invention.
- Figs. 2A, 2B and 2C show the gate voltage, drain current and drain voltage, respectively, as a function of time (t) for a fast turn-off LDMOS switching power transistor. As shown in Fig 2C, a large ringing or oscillation voltage appears at the drain of the LDMOS power switch when it turns off.
- Figs. 2D, 2E and 2F show the corresponding waveforms of gate voltage, drain current and drain voltage, respectively, when a slow turn-off LIGBT device is used as the power switch.
- the drain current decreases relatively slowly upon turn-off of the LIGBT device, resulting in a very substantial reduction in the amplitude of the ringing voltage developed at the drain of the LIGBT device (Fig. 2F).
- the current in the slow turn-off LIGBT device goes to zero relatively slowly, which allows the energy in the parasitic inductance 20 to gradually decay to zero thereby reducing the voltage ring at the drain of the LIGBT switching device 12.
- a slow turn-off LIGBT device operating at a low frequency as the power switching device in a pre-regulator circuit results in a power integrated circuit AC to DC converter circuit (pre-regulator) having a high efficiency and low EMI, and providing good regulation for a 1A load current with a variable DC output voltage from 24V to 150V and with an AC input voltage range of from 30V to 260V.
- An IC pre-regulator AC/DC converter circuit in accordance with the invention was tested in a 13 inch TV receiver and exhibited much lower EMI noise, especially above 6MHz, than a conventional high frequency switch mode power supply.
Description
Claims (6)
- An AC/DC converter circuit comprising:a pair of input terminals (1, 2) for connection to a source of AC supply voltage for the converter circuit,a pair of DC output terminals (5, 6) for supplying a load adapted to be coupled to said output terminals (5, 6),a rectifier circuit (3) coupled between the input terminals (1, 2) and the output terminals (5, 6),a load capacitor (4) coupled to said output terminals (5, 6),a switching transistor (12) connected in series circuit with the load capacitor (4) to output terminals of the rectifier circuit (3), anda control circuit (17) having an output coupled to a control electrode of the switching transistor (12) to supply a control signal that will turn off the switching transistor (12) at a predetermined level of the output voltage, characterized in that the switching transistor (12) is a slow turn-off switching transistor,the AC/DC converter circuit further having a parasitic inductance (20) that normally produces a large ringing voltage at the drain electrode of the switching transistor (12), said slow turn-off transistor being responsive to said control signal to slow the decay of current therein and thereby slow the decay of current in the parasitic inductance (20) so as to reduce the level of the ringing voltage on turn-off of the switching transistor (12).
- The AC/DC convener circuit as claimed in Claim 1 wherein said slow turn-off switching transistor (12) comprises a lateral insulated gate bipolar transistor (LIGBT) device.
- The AC/DC converter circuit as claimed in Claim 2 wherein said control circuit (17) comprises:a differential voltage sensor (7) having an input coupled to said load capacitor (4) and an output (9) coupled to the control electrode of the LIGBT device (12), anda drain voltage sensor (11) coupled to the drain electrode of the LIGBT device (12) and an output coupled to the control electrode thereof.
- The AC/DC converter circuit as claimed in Claim 1, wherein said slow turn-off switching transistor (12) comprises a LIGBT device.
- The AC/DC converter circuit as claimed in Claim 1, wherein said control circuit (17) comprises:a differential voltage sensor (7) having an input coupled to said load capacitor (4) and an output (9) coupled to the control electrode of the LIGBT device (12), anda drain voltage sensor (11) coupled to the drain electrode of the LIGBT device (12) and an output coupled to the control electrode thereof.
- The AC/DC converter circuit as claimed in Claim 5, wherein said control circuit (17) further comprises a logic circuit (10) coupled between the respective outputs of the differential voltage sensor (7) and the drain voltage sensor (11) and the control electrode of the slow turn-off switching transistor (12).
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US345167 | 1989-05-01 | ||
US08/345,167 US5687065A (en) | 1994-11-28 | 1994-11-28 | Pre-regulator with light switch to limit voltage ringing on turn-off |
PCT/IB1995/000830 WO1996017424A2 (en) | 1994-11-28 | 1995-10-03 | Pre-regulator with protection against voltage ringing on turn-off |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0746892A1 EP0746892A1 (en) | 1996-12-11 |
EP0746892B1 true EP0746892B1 (en) | 2000-03-15 |
Family
ID=23353839
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP95931389A Expired - Lifetime EP0746892B1 (en) | 1994-11-28 | 1995-10-03 | Pre-regulator with protection against voltage ringing on turn-off |
Country Status (7)
Country | Link |
---|---|
US (1) | US5687065A (en) |
EP (1) | EP0746892B1 (en) |
JP (1) | JPH09509040A (en) |
KR (1) | KR970700951A (en) |
DE (1) | DE69515648T2 (en) |
TW (1) | TW281825B (en) |
WO (1) | WO1996017424A2 (en) |
Families Citing this family (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3230434B2 (en) * | 1996-06-05 | 2001-11-19 | 富士電機株式会社 | AC / DC conversion circuit |
DE19836577C1 (en) * | 1998-08-12 | 2000-04-20 | Siemens Ag | Power circuit with reduced interference |
JP3633522B2 (en) * | 2001-07-27 | 2005-03-30 | 株式会社デンソー | Load drive circuit |
US6583998B2 (en) | 2001-09-17 | 2003-06-24 | Bose Corporation | Power supply regulating having novel charging circuitry |
US7119398B1 (en) * | 2004-12-22 | 2006-10-10 | Actel Corporation | Power-up and power-down circuit for system-on-a-chip integrated circuit |
US8830637B2 (en) | 2010-08-31 | 2014-09-09 | Texas Instruments Incorporated | Methods and apparatus to clamp overvoltages for alternating current systems |
CN103051170B (en) * | 2012-12-28 | 2015-06-03 | 上海贝岭股份有限公司 | Audio-frequency noise eliminating circuit |
CN105465847A (en) * | 2016-01-13 | 2016-04-06 | 昂宝电子(上海)有限公司 | Analog control system for electromagnetic oven and electromagnetic oven |
JP6905711B2 (en) * | 2017-08-02 | 2021-07-21 | リコー電子デバイス株式会社 | Overvoltage protection circuit and power supply |
CN109889031B (en) * | 2019-04-11 | 2021-05-11 | 广东美的制冷设备有限公司 | Operation control method, device, circuit, household appliance and computer storage medium |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4989058A (en) * | 1985-11-27 | 1991-01-29 | North American Philips Corp. | Fast switching lateral insulated gate transistors |
US4683529A (en) * | 1986-11-12 | 1987-07-28 | Zytec Corporation | Switching power supply with automatic power factor correction |
US4860152A (en) * | 1989-01-30 | 1989-08-22 | Delco Electronics Corporation | Two stage protection circuit for a power MOSFET driving an inductive load |
JPH0834709B2 (en) * | 1990-01-31 | 1996-03-29 | 株式会社日立製作所 | Semiconductor integrated circuit and electric motor control device using the same |
DE4039404A1 (en) * | 1990-12-10 | 1992-06-11 | Sgs Thomson Microelectronics | OVERVOLTAGE PROTECTION DEVICE |
US5289361A (en) * | 1991-01-16 | 1994-02-22 | Vlt Corporation | Adaptive boost switching preregulator and method |
US5301095A (en) * | 1991-10-01 | 1994-04-05 | Origin Electric Company, Limited | High power factor AC/DC converter |
US5436824A (en) * | 1992-12-10 | 1995-07-25 | Rosemount Inc. | Inrush current limiter in a magnetic flowmeter |
US5469046A (en) * | 1993-04-30 | 1995-11-21 | North American Philips Corporation | Transformerless low voltage switching power supply |
US5371667A (en) * | 1993-06-14 | 1994-12-06 | Fuji Electrochemical Co., Ltd. | Electric power supply |
-
1994
- 1994-11-28 US US08/345,167 patent/US5687065A/en not_active Expired - Lifetime
-
1995
- 1995-10-03 EP EP95931389A patent/EP0746892B1/en not_active Expired - Lifetime
- 1995-10-03 WO PCT/IB1995/000830 patent/WO1996017424A2/en active IP Right Grant
- 1995-10-03 KR KR1019960704165A patent/KR970700951A/en not_active Application Discontinuation
- 1995-10-03 JP JP8518499A patent/JPH09509040A/en active Pending
- 1995-10-03 DE DE69515648T patent/DE69515648T2/en not_active Expired - Fee Related
- 1995-10-09 TW TW084110610A patent/TW281825B/zh active
Also Published As
Publication number | Publication date |
---|---|
WO1996017424A3 (en) | 1996-08-29 |
US5687065A (en) | 1997-11-11 |
EP0746892A1 (en) | 1996-12-11 |
JPH09509040A (en) | 1997-09-09 |
KR970700951A (en) | 1997-02-12 |
TW281825B (en) | 1996-07-21 |
WO1996017424A2 (en) | 1996-06-06 |
DE69515648D1 (en) | 2000-04-20 |
DE69515648T2 (en) | 2000-09-21 |
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